How do voluntary muscles differ from involuntary muscles?

Voluntary muscles are striated. These are your skeletal muscles, controlled by the somatic nervous system. This means that you are able to manipulate the movement of these muscle types. Involuntary muscles are not usually striated, though the heart muscle has some striation. Most involuntary muscle is smooth muscle. These are controlled by the autonomic nervous system, which can be broken down into sympathetic and parasympathetic nervous systems. The sympathetic nervous system usually is referred to as the part that causes contraction of muscle, speeding of heart (increased contraction), etc. Parasympathetic is like the "relaxed" state. Contractions decline, etc.